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From: Tom Zanussi <tom.zanussi@linux.intel.com>
To: "Woegerer, Paul" <Paul_Woegerer@mentor.com>
Date: Mon, 14 Oct 2013 11:32:46 -0500
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Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Christopher Larson <chris_larson@mentor.com>,
	openembedded-core@lists.openembedded.org
Subject: Re: lttng-modules may trigger deadlock in the timekeeping subsystem with Linux <= 3.10.13, <= 3.11.2
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On Mon, 2013-10-14 at 17:54 +0200, Woegerer, Paul wrote:
> Hi,
> 
> looking at the following commits shows that the current version of
> lttng-modules 2.3.x can trigger a deadlock in the timekeeping subsystem
> of Linux.
> 
> http://git.lttng.org/?p=lttng-modules.git;a=commit;h=fc8216ae9ec5d18172d8227d179475e7cc1fb45c
> http://git.lttng.org/?p=lttng-modules.git;a=commit;h=9998f5216f4641a79e158135c4c1658dcc6cd2d8
> http://git.lttng.org/?p=lttng-modules.git;a=commit;h=e14bf96416c39675a5f785b032d1c5279020b93d
> 
> This is caused by a bug in the kernel that was introduced in 3.10. The
> problem is already fixed in Linux 3.10.14, 3.11.3 and 3.12. See:
> http://marc.info/?l=linux-kernel&m=137894350929349
> 
> lttng-modules 2.3.2 contains preprocessor-code that makes sure that
> building of lttng-modules fails for the unlucky combinations of kernel
> and lttng-modules. The problem is when we update our lttng-modules 2.3.0
> to 2.3.2 then we would have lttng-modules failing to build for our qemu*
> MACHINEs.
> 
> Any recommendations on how we should address this ?
> 

Probably just get Bruce to update linux-yocto-3.10 to 3.10.14, or pull
the specific commit that fixes it in.

Tom

> Many thanks,
> Paul
>